(b) may not be necessary: hitting military bases, and munition and fuel stores, neither of which are moving targets, is a useful capability.
Also consider that russia's Kinzhal can go about mach 4-5. That sounds pretty bad, until you realize that good old ICBMs re-enter from space and travel in atmosphere somewhere between mach 15 and 20.
Fast missiles like Kinzhal are not new at all. As far back as the 60s the USA had the Sprint and Nike which could accelerate from the ground to mach 10 in seconds and would glow white hot from heating. Even maneuverable glide vehicles aren't new, the Pershing II could perform limited course changes during descent back in the early 80s. Yes, fast missiles are scary, but they're not in the same class as true air-breathing hypersonic weapons.
https://en.wikipedia.org/wiki/Nike_Zeus
So it's impossible to gauge the accuracy of anything let alone the rarely seen Kinzhal missiles.
Nothing in the Ukraine fits this description. Those are ordinary ballistic missiles, which naturally have hypersonic ballistic re-entry. There is nothing interesting about that, we've had it for 70+ years now.
Lots of claims of both but no actual evidence.